Downhole tool with turbine-powered pump

ABSTRACT

A tool for moving within a passage comprises an elongated body, at least one gripper assembly engaged with the body, a turbine, and a power transmission assembly. The elongated body has an internal fluid chamber and is configured to be secured to a fluid conduit so that a first fluid flowing through the conduit flows into the internal fluid chamber. The gripper assembly has an actuated position in which the gripper assembly grips onto an inner surface of the passage to substantially limit relative movement between the gripper assembly and the inner surface. The gripper assembly also has a retracted position in which the gripper assembly permits substantially free relative movement between the gripper assembly and the inner surface of the passage. The turbine is configured to receive the first fluid flow through the internal fluid chamber, the turbine having an output shaft configured to rotate as the first fluid flows through the turbine. The power transmission assembly is configured to convert rotation of the output shaft into power for moving the gripper assembly to its actuated position.

INCORPORATION BY REFERENCE

The present application incorporates by reference the entire disclosuresof U.S. Pat. No. 6,003,606 (entitled “PULLER-THRUSTER DOWNHOLE TOOL”);U.S. Pat. No. 6,347,674 (“ELECTRICALLY SEQUENCED TRACTOR”); U.S. Pat.No. 6,241,031 (“ELECTRO-HYDRAULICALLY CONTROLLED TRACTOR”); U.S. Pat.No. 6,679,341 (“TRACTOR WITH IMPROVED VALVE SYSTEM”); U.S. Pat. No.6,464,003 (“GRIPPER ASSEMBLY FOR DOWNHOLE TRACTORS”); and U.S. Pat. No.6,715,559 (“GRIPPER ASSEMBLY FOR DOWNHOLE TRACTORS”). The presentapplication also incorporates by reference the entire disclosures ofU.S. Patent Application Publication Nos. 2004/0168828 (“TRACTOR WITHIMPROVED VALVE SYSTEM”); and 2005/0247488 (“ROLLER LINK TOGGLE GRIPPERAND DOWNHOLE TRACTOR”). The present application also incorporates byreference the entire disclosure of U.S. Provisional Patent ApplicationNo. 60/781,885, filed Mar. 13, 2006 (“EXPANDABLE RAMP GRIPPER”).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to tools for conductingoperations within passages, and specifically to tools for boreholeintervention and/or drilling.

2. Description of the Related Art

U.S. Pat. No. 6,003,606, entitled “Puller-Thruster Downhole Tool,”discloses an innovative self-propelled tool or tractor for drilling,completion, stimulation, and intervention that pulls a drill string andsimultaneously thrusts itself and its payload downhole and/or into acasing or borehole formation. The '606 patent discloses a tractor thatincludes one or more gripper assemblies (e.g., bladders or packerfeet)that grip onto an inner surface of a borehole or casing, and one or morepropulsion assemblies that propel the tractor body forward when at leastone of the gripper assemblies is gripping the borehole. A valve systemdirects a fluid (e.g., drilling mud, intervention fluid, hydraulicfluid) to and from the gripper assemblies and propulsion assemblies topower movement of the tractor.

The '606 patent discloses two basic types of tractor configurations—openloop and closed loop. The open loop system uses an externally providedfluid as a medium of hydraulic communication within the tractor. Theopen loop consists of a ground surface pump, tubing extending from thepump into a borehole, a tractor within the borehole and connected to thetubing, and an annulus between the exterior of the tractor and an innersurface of the borehole. The fluid is pumped down through the tubing tothe tractor, used by the tractor to move and conduct other downholeoperations, and then forced back up the borehole through the annulus.The tractor is powered by differential pressure—the difference of thepressure at the point of intake of fluid to the tractor and the pressureof fluid ejected from the tractor into the annulus. In the open loopsystem, a portion of the fluid is used to power the tractor's movementand another portion of the fluid flows through the tractor for variousdownhole purposes, such as hole cleaning, sand washing, acidizing, andlubricating of a drill bit (in drilling operations). Both portions ofthe fluid return to the ground surface through the annulus.

The '606 patent also discloses a closed loop configuration in which ahydraulic fluid is circulated through the gripper assemblies andpropulsion assemblies to power the tractor's movement within theborehole. In particular, FIG. 19 of the '606 patent discloses a downholemotor that powers the recirculation of the hydraulic fluid.

U.S. Pat. Nos. 6,347,674; 6,241,031; and 6,679,341, as well as U.S.Patent Application Publication No. 2004/0168828, disclose alternativevalve systems and methods for directing fluid to and from a downholetractor's gripper assemblies and propulsion assemblies for moving thetractor.

SUMMARY

In one aspect, a tool for moving within a passage is provided. The toolcomprises an elongated body, at least one gripper assembly engaged withthe body, a turbine, and a power transmission assembly. The elongatedbody has an internal fluid chamber and is configured to be secured to afluid conduit so that a first fluid flowing through the conduit flowsinto the internal fluid chamber. The gripper assembly has an actuatedposition in which the gripper assembly grips onto an inner surface ofthe passage to substantially limit relative movement between the gripperassembly and the inner surface. The gripper assembly also has aretracted position in which the gripper assembly permits substantiallyfree relative movement between the gripper assembly and the innersurface of the passage. The turbine is configured to receive the firstfluid flow through the internal fluid chamber, the turbine having anoutput shaft configured to rotate as the first fluid flows through theturbine. The power transmission assembly is configured to convertrotation of the output shaft into power for moving the gripper assemblyto its actuated position.

In another aspect, a method of moving a tool within a passage isprovided. An elongated body having an internal fluid chamber isprovided. The body is secured to a fluid conduit so that a first fluidflowing through the conduit flows into the internal fluid chamber of thebody. At least one gripper assembly is provided and engaged with thebody. The gripper assembly has an actuated position in which the gripperassembly grips onto an inner surface of the passage to substantiallylimit relative movement between the gripper assembly and the innersurface, and a retracted position in which the gripper assembly permitssubstantially free relative movement between the gripper assembly andthe inner surface of the passage. A turbine is provided, the turbineconfigured to receive the first fluid flow through the internal fluidchamber. The turbine has an output shaft configured to rotate as thefirst fluid flows through the turbine. A power transmission assembly isprovided, the power transmission assembly configured to convert rotationof the output shaft into power for moving the gripper assembly to itsactuated position. The first fluid is pumped through the conduit intothe internal fluid chamber of the body and through the turbine.

For purposes of summarizing the invention and the advantages achievedover the prior art, certain objects and advantages of the invention havebeen described herein above. Of course, it is to be understood that notnecessarily all such objects or advantages may be achieved in accordancewith any particular embodiment of the invention. Thus, for example,those skilled in the art will recognize that the invention may beembodied or carried out in a manner that achieves or optimizes oneadvantage or group of advantages as taught herein without necessarilyachieving other objects or advantages as may be taught or suggestedherein.

All of these embodiments are intended to be within the scope of theinvention herein disclosed. These and other embodiments of the presentinvention will become readily apparent to those skilled in the art fromthe following detailed description of the preferred embodiments havingreference to the attached figures, the invention not being limited toany particular preferred embodiment(s) disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a conventional coiled tubing tractorsystem.

FIG. 2 is a schematic diagram of a closed loop system for powering adownhole tractor, according to one embodiment of the invention.

FIG. 3 is a more detailed schematic diagram of the closed loop system ofFIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates a conventional coiled tubing tractor or tool forconducting downhole operations such as intervention and drilling. Theillustrated system is an open loop configuration. The coiled tubingsystem 100 typically includes a power supply 102 for poweringground-level equipment, a tubing reel 104, a tubing guide 106, and atubing injector 110, which are well known in the art. The illustratedsystem includes a bottom hole drilling assembly 120 for drilling aborehole 132 with a drill bit 130. However, other types of bottom holeassemblies 120 can alternatively be provided, such as those forintervention operations like hole cleaning, sand washing, acidizing, andthe like. As known, coiled tubing 114 is inserted into the borehole 132,and a fluid (e.g., drilling mud, intervention fluid) is typically pumpedthrough the inner flow channel of the coiled tubing 114 towards thedrill bit 130 located at the end of the drill string. Positioned betweenthe drill bit 130 and the coiled tubing 114 is a tool or tractor 112.The illustrated bottom hole assembly (BHA) 120 includes a number ofelements known to those skilled in the art, such as a downhole motor 122and a Measurement While Drilling (MWD) system 124. The tractor 112 ispreferably connected to the coiled tubing 114 and the bottom holeassembly 120 by connectors 116 and 126, respectively, as known in theart. In this system, the fluid is pumped through the inner flow channelof the coiled tubing 114 and through the tractor 112 to the drill bit130. The fluid and drilling debris return to the surface in the annulusdefined between the exterior surface of the tractor 112 and the innersurface of the borehole 132, and also defined between the exteriorsurface of coiled tubing 114 and the inner surface of the borehole 132.

When operated, the tractor 112 is configured to move within the borehole132. This movement allows, for example, the tractor 112 to maintain apre-selected force on the bottom hole assembly 120 such that the rate ofmovement or drilling can be controlled. The tractor 112 can be used tomove various types of equipment through the borehole 132. For example,it will be understood that the tractor 112 can be connected with orinclude, without limitation, a downhole motor (for rotating a drillbit), steering system, instrumentation sub (an instrumented package thatcontrols various aspects of downhole operation, including shockvibration, weight on bit, torque at bit, rate of penetration, downholemotor rpm, and differential pressure across motor), Measurement WhileDrilling apparatus (an apparatus for measuring gyroscopic data such asazimuth, inclination, and measured depth), drill bit, mechanical andhydraulic disconnect for intervention, jetting tools, production loggingtools (including apparatus for measuring and recording, withoutlimitation, temperature, annulus pressure, and various flow rates),drilling logging tools (for measuring and recording, without limitation,resistivity measurements, magnetic resonance (MRI), sonic neutrondensity, density, fluid identification, and gamma ray measurements),perforation guns, casing collar locators, and torque limiting tools (fordrilling).

A closed loop configuration has relevant differences from an open loopsystem that operates on differential pressure (the difference inpressure between the bore of the tractor and the exterior of thetractor). With an open system, a restriction in the system is requiredto produce a pressure difference (decrease) between the interior andexterior of the tractor. Typically, the restriction is an orifice suchas a fixed diameter nozzle, and is not capable of being adjusted fromthe surface. For typical coiled tubing rig operations, the effectivemeans of control is to control the surface pump output flow rate.However, the differential pressure available at the tractor is aquadratic (non-linear) function of the surface pump output flow rate.Thus, doubling the surface pump output flow rate will increase thedifferential pressure through an in-series fixed orifice by a factor offour. This makes power control of the tractor more difficult as normaloperational changes can have non-linear impact on tractor power,requiring additional features to be incorporated into the open looppowered tractor to restrict the amount of pressure delivered to thegripper assemblies, for example. Further, this has a disadvantage inthat the normal operating range of the surface pump output flow raterequired for various operations may have to be restricted, thus reducingcleaning efficiency during the operation.

FIG. 2 is a schematic illustration of a turbine-powered pump forcirculating hydraulic fluid in a closed loop for powering a downholetool or tractor, according to one embodiment of the present invention.In this configuration, a first fluid (typically drilling/interventionfluid) that is externally pumped into the coiled tubing typically at theground surface flows through the tractor and passes through a turbine150 on its way to the remaining bottom hole assembly (typically securedto the distal end of the tractor). The flow through the turbine 150produces rotation of the turbine's output shaft, which drives a pump 154through a gearbox 152. The pump 154 circulates a second fluid (typicallya different type of fluid than the first fluid, such as, for example,hydraulic fluid) in a closed system loop 156. Box 158 represents a valvesystem, gripper assemblies, and propulsion assemblies as known in theart. For example, the valve system, gripper assemblies, and propulsionassemblies can be substantially as shown and described in U.S. Pat. Nos.6,003,606; 6,347,674; 6,241,031; and 6,679,341, as well as U.S. PatentApplication Publication No. 2004/0168828. Also, the gripper assembliescan be substantially as shown and described in U.S. Pat. Nos. 6,464,003and 6,715,559; U.S. Patent Application Publication No. 2005/0247488; andU.S. Provisional App. No. 60/781,885. The second fluid provideshydraulic force for operation of the gripper assemblies and propulsionassemblies, and in some cases the valves.

FIG. 3 is a more detailed schematic illustration of the closed loopsystem of FIG. 2 adapted for use with a variation of the Puller-ThrusterDownhole Tool (also referred to as the “Puller-Thruster Assembly” or“PTA”) described in U.S. Pat. No. 6,003,606. As the first fluid ispumped through the turbine 150, the turbine output shaft rotates topower the pump 154 via the gearbox 152 (not shown), and the pump 154 inturn circulates the second fluid through the illustrated valve assembly.The second fluid flows from a supply line 228 through a start/stop valve160 (also known as an “idler valve”) into the valve system. A six-waycontrol valve 162 shuttles back and forth to direct the fluid to andfrom an aft gripper assembly 180 (illustrated as a deflated packerfoot)and a forward gripper assembly 182 (illustrated as an inflatedpackerfoot), and also to and from an aft propulsion assembly 184 and aforward propulsion assembly 186 (each propulsion assembly comprisingbarrels and internal pistons, as taught in the '606 patent). Valves 164and 166 (also known as “directional control valves”) control theshuttling and position of the six-way control valve 162. Packerfeetvalves 168 and 170 regulate the flow of fluid into the packerfeet 180and 182. A reverser valve 172 controls the direction of tractor movement(i.e., uphole or downhole). The operation of these valves is understoodfrom the teachings of the aforementioned patents incorporated byreference. A sump 157 is preferably provided to store a reservoir of thesecond fluid. The circulating second fluid returns to the sump 157 via areturn line 230.

FIG. 3 shows an embodiment of a tool 200 (illustrated as aPuller-Thruster Assembly) positioned within a drilled hole 205 inside arock formation 212. The tool 200 includes an elongated body formed ofcentral coaxial cylinders 207. The aft gripper assembly 180, aftpropulsion assembly 184, forward gripper assembly 182, and forwardpropulsion assembly 186 are engaged on the central coaxial cylinders207. The aft propulsion assembly 184 includes annular pistons 218secured to the cylinders 207. Similarly, the forward propulsion assembly186 includes annular pistons 220 secured to the cylinders 207. Thenumber of pistons can vary (e.g., up to 20 pistons) and depends on thedesired thrust and pull loads.

The tool body defines an internal mud flow passage 224 inside thecylinders 207. The aft end of the tool body has an inlet 201 connectedto coiled tubing 114 via a coiled tubing connector 206 (connection canbe threaded or snapped together). While FIG. 3 shows coiled tubing 114,the tool 200 can also be used with rotary drill rigs instead. Theforward end of the tool body is connected to a bottom hole assembly(BHA) 204. The illustrated tool includes a female coiled tubingconnector 208 and stabilizers 210. The valve control pack 214 ispositioned between the forward and aft gripper assemblies and alsobetween the forward and aft propulsion assemblies. Splines 216 canoptionally be incorporated between the central coaxial cylinders 207 andthe gripper assemblies to prevent the transmission of torque from theBHA 204 to the coiled tubing 114.

In use, drilling/intervention fluid flows from the coiled tubing 114into the inlet 201 of the tool body, and downhole (toward the bottom ofthe hole) through the mud flow passage 224. The fluid flows through theturbine 150, powering the pump 154. The fluid continues through thepassage 224 into the BHA 204, exiting the BHA 204 through an outlet 203.The inlet 201 and outlet 203 are also shown in relation to the turbine150 on the bottom right hand side of FIG. 3. The drilling/interventionfluid that exits via the outlet 203 then flows uphole to the groundsurface through an annulus defined between the tool 200 and the drilledhole 205.

The upper right hand side of FIG. 3 includes a cross-sectional view ofthe inflated packerfoot 182, taken along line A-A. The illustratedpackerfoot 182 includes three inflated sections. Three mud flow returnpaths 222 are defined between the three inflated sections of thepackerfoot. These return paths 222 allow drilling fluid that exits viathe outlet 203 to flow back uphole past the inflated packerfoot. It willbe understood that the aft packerfoot 180 can be substantially identicalto the forward packerfoot 182. The illustrated packerfoot cross sectionshows the packerfoot inflated radially beyond the outside diameter 226of the tool 200.

A relevant advantage of using a turbine-powered pump as illustrated isthat the system is flow-based, meaning that the downhole tractor can bemore easily controlled by the surface pump that pumps fluid down intothe coiled tubing toward the turbine. With a flow-based system, anychange in the surface pump output volume flow rate linearly changes thepower available to the tractor. Since the surface pump output flow ratecan be relatively easily adjusted dynamically during tractor operation,the resulting adjustment of the power to the tractor provides enhancedcontrol over the tractor's speed and pulling force. This enhancedcontrol is available over a substantial operating range of surface pumpoutput flow rates. This is convenient for some types of operations. Forexample, during sand washing it is desirable to provide a maximum amountof fluid into the borehole while the tractor continues its forwardmovement, usually at near-maximum pulling capacity.

Another relevant advantage of this system is that the pump 154 isdesirably directly powered by the rotating output of the turbine/gearboxcombination, without any intermediate steps (e.g., electrical powergeneration from the turbine output, and use of such electrical power todrive an electric motor that drives the pump). The provision of suchintermediate steps would introduce a risk of a loss of efficiency inconverting the kinetic energy of the first fluid pumped into the turbine150 into power for driving the operation of the pump 154. The disclosedturbine/gearbox combination advantageously provides a highly efficientconversion of the first fluid's kinetic energy.

Although this invention has been disclosed in the context of certainpreferred embodiments and examples, it will be understood by thoseskilled in the art that the present invention extends beyond thespecifically disclosed embodiments to other alternative embodimentsand/or uses of the invention and obvious modifications thereof. Thus, itis intended that the scope of the present invention herein disclosedshould not be limited by the particular disclosed embodiments describedabove.

1. A tool for moving within a passage, comprising: an elongated bodyhaving an internal fluid chamber, the body configured to be secured to afluid conduit so that a first fluid flowing through the conduit flowsinto the internal fluid chamber of the body; at least one gripperassembly engaged with the body, the gripper assembly having an actuatedposition in which the gripper assembly grips onto an inner surface ofthe passage to substantially limit relative movement between the gripperassembly and the inner surface, the gripper assembly having a retractedposition in which the gripper assembly permits substantially freerelative movement between the gripper assembly and the inner surface ofthe passage; a turbine configured to receive the first fluid flowthrough the internal fluid chamber, the turbine having an output shaftconfigured to rotate as the first fluid flows through the turbine; and apower transmission assembly configured to convert rotation of the outputshaft into power for moving the gripper assembly to its actuatedposition.
 2. The tool of claim 1, wherein the tool includes a closedsystem for converting a circulating flow of a second fluid into movementof the tool within the passage, the closed system comprising: the atleast one gripper assembly, the gripper assembly configured to utilizefluid pressure to move to its actuated position; at least one propulsionassembly on the body, the propulsion assembly configured to utilizefluid pressure to propel the body within the passage when the gripperassembly is in its actuated position; a valve assembly configured todirect fluid to and from the gripper assembly and the propulsionassembly to produce movement of the body within the passage; and a pumpconfigured to circulate the second fluid through the closed system;wherein rotation of the output shaft powers the pump.
 3. The tool ofclaim 2, further comprising a gearbox operatively connected between thepump and the output shaft of the turbine.
 4. The tool of claim 1,wherein the power transmission assembly comprises a pump.
 5. The tool ofclaim 1, wherein the conduit comprises coiled tubing.
 6. A method ofmoving a tool within a passage, comprising: providing an elongated bodyhaving an internal fluid chamber; securing the body to a fluid conduitso that a first fluid flowing through the conduit flows into theinternal fluid chamber of the body; providing at least one gripperassembly engaged with the body, the gripper assembly having an actuatedposition in which the gripper assembly grips onto an inner surface ofthe passage to substantially limit relative movement between the gripperassembly and the inner surface, the gripper assembly having a retractedposition in which the gripper assembly permits substantially freerelative movement between the gripper assembly and the inner surface ofthe passage; providing a turbine configured to receive the first fluidflow through the internal fluid chamber, the turbine having an outputshaft configured to rotate as the first fluid flows through the turbine;providing a power transmission assembly configured to convert rotationof the output shaft into power for moving the gripper assembly to itsactuated position; pumping the first fluid through the conduit into theinternal fluid chamber of the body and through the turbine.